Quartz members have been widely used in various substrate processing apparatuses, for example, for fabricating semiconductor devices, because quartz has a high melting point and less degassing under a reduced atmosphere environment. In addition, the quartz members may have less adverse effect as a source of contamination on semiconductor devices such as highly sophisticated devices. Therefore, the quartz members are preferable for the substrate processing apparatuses, which require a strict control of contamination.
However, even when quartz material to be used for making the quartz members is highly purified, the quartz material may be contaminated, for example, when the material is machined into the quartz members. If the quartz members contaminated during machining are used in the substrate processing apparatus for fabricating the semiconductor devices, semiconductor wafers may also be contaminated, thereby reducing the production yield of the semiconductor devices.
In order to address such a disadvantage, various methods have been proposed to detect metal contamination in the quartz members. One of the examples of such methods is to detect (analyze) metal contamination of the quartz members by immersing the quartz members into an etchant which in turn is analyzed (see Patent Document 1 listed below).
Patent Document 1: Japanese Laid-Open Patent Application No. 2001-223251.